This invention relates to certain 2,2-dithiolethylene derivatives and the manufacture thereof. In a further aspect the invention relates to the use of such derivatives as antiwear or extreme pressure additives in lubricating composition to prevent or reduce wear and corrosion between sliding or contacting moving parts and to lubricating composition and hydraulic or functional fluids containing such additives.
Antiwear agents and extreme pressure agents are used to provide wear projection in a variety of lubricating compositions including internal composition engine oils, gear oils, transmission fluids, industrial oils, cutting oils, greases and the like. Engine oils which provide wear protection are very important for automobile spark ignition and diesel engines because such engines have valve train systems, including valves, cams and rocker arms which present special lubrication concerns. It is extremely important that the lubricant, i.e., the engine oil, protects these parts from wear. Engine oils use a mineral oil or a synthetic oil as a base oil. However, simple base oils alone do not provide the necessary properties to provide the necessary wear protection, deposit control, etc., required to protect internal combustion engines. Thus, base oils are formulated with various additives for imparting auxiliary functions, such as ashless dispersants, metallic detergents (i.e., metal-containing detergents), antiwear agents, antioxidants (i.e., oxidation inhibitors), viscosity index improvers and the like to give a compounded oil (i.e., a lubricating oil composition).
A number of such engine oil antiwear additives are known and employed in practice. Zinc dialkyldithiophosphates are, for example, because of their favorable characteristics as an antiwear agent and performance as an oxidation inhibitor, contained in most all of the commercially available internal composition engine oils, especially those used for automobiles.
However, a problem has arisen with respect to the use of zinc dialkyldithiophosphate, because phosphorous derivatives poison catalyst components of catalytic converters. This is a major concern, because effective catalytic converters are needed to reduce pollution and to meet governmental regulation designed to reduce toxic gases, such as hydrocarbons, carbon monoxide, ad nitrogen oxides, in internal combustion engine exhaust emission. Such catalytic converters generally use a combination of catalytic metals, such as platinum or variations, and metal oxides and are installed in the exhaust streams, e.g., the exhaust pipes of automobiles, to convert the toxic gases to nontoxic gases. As before mentioned these catalyst components are poisoned by the phosphorous component, or the phosphorous decomposition products of the zinc dialkyldithiophosphate; and accordingly, the use of engine oils containing phosphorous additives may substantially reduce the life and effectiveness of catalytic converters. Therefore, it would be desirable to reduce the phosphorous content in the engine oils so as to maintain the activity and extend the life of the catalytic converter. However, simply decreasing the amount of zinc dialkyldithiophosphate presents problems because this necessarily lowers the antiwear properties and oxidation inhibition properties of the lubricating oil. Therefore, it is necessary to find a way to reduce phosphorous content while still retaining the antiwear and oxidation or corrosion inhibiting properties of the higher phosphorous content engine oils.
In order to compensate for lowering the amount of zinc dialkyldithiophosphate, the use of other oxidation inhibitors such as phenol derivatives and amine derivatives have been studied. However, the use of such known oxidation inhibitors in place of zinc dialkyldithiophosphate at best only marginally satisfies the required levels of antiwear and oxidation inhibition. The use of magnesium sulfonate detergents which are also effective to enhance the antiwear properties in valve train systems has also been studied and, in fact, some commercially available engine oils use a magnesium sulfonate detergent. However, engine oils containing a magnesium sulfonate detergent have drawbacks in that crystalline precipitates are sometimes produced when these engine oils are stored under humid or variable temperature conditions for a long period of time. Such precipitates may cause plugging of the filter which is installed in the engine oil circulating system. Such plugging is more likely to occur when a large amount of the magnesium sulfonate detergent is used so as to enhance the desired antiwear properties. Thus, the use of magnesium sulfonate detergents is not a satisfactory solution. At the present time, demand for further decrease of phosphorous content is very high from the viewpoint of the aforementioned problems. For instance, it is sometimes desired to decrease the phosphorous content to levels below the regulated upper limit and the 0.1 wt. % phosphorous level of today's better engine oil. This reduction cannot be satisfied by the present measures in practice and still meet the severe antiwear and corrosion inhibiting properties required of today's engine oils.
Thus, it would be desirable to develop lubricating oils, and additives and additive packages therefore, having low levels of phosphorous but which still provide the needed wear protection and corrosion protection now provided by lubricating oils having higher levels of zinc dialkyldithiophosphate, but which do not suffer from the disadvantages of the low phosphorous level lubricants discussed above. There is also a continuing need for antiwear and extreme pressure additives in oil based lubricating compositions generally including transmission fluids, heavy machinery gear oils, hydraulic tractor fluids, industrial fluids, cutting oils and greases.
U.S. Pat. No. 4,042,514 discloses certain 5-alkylthio and 5-alkylarylthio-1,2-thiole-3-thiones and 3-ones and the use of such compounds as extreme pressure and antioxidant additives for lubricating compositions. Based on U.S. Pat. No. 4,042,514 (Col. 1, lines 10-15), U.S. Pat. Nos. 2,653,910; 2,995,569 and 3,673,090 disclose certain alkyl-or aryldithiole-thiones obtained by the sulfurization of polyisobutene as extreme-pressure, antiwear oil antioxidant lubricating oil additives. Canadian Patent No. 1,228,847 describes the use of aliphatic olefins in combination with certain sulfurized olefins to provide wear protection in hydrorefined lubricating oils. U.S. Pat. Nos. 4,119,549; 4,147,640; 4,148,737; 4,191,659 describe the use of various sulfurized compounds including sulfurized olefins, carboxylic acid esters, esterolefins, etc., as antioxidants or antiwear or extreme pressure additives for lubricating oil. Although a number of sulfurized organic compounds have been proposed as wear additives and extreme pressure agents or antioxidants, one cannot predict that a given sulfur containing organic compound or class of compounds will have any of these properties or even if they possess one or more of these properties that they will be compatible with the other components of the lubricating composition or will not in fact themselves create additional problems, notably copper corrosion.
U.S. Pat. No. 3,876,550 (issued 1975) discloses lubricating compositions containing an alkylene bis(dithiocarbamate), as an antioxidant, and a substituted succinic acid as a rust inhibitor. The alkylene dithiocarbamate is represented in the patent by the formula R.sup.1 R.sup.2 N-C(S)-S-alkylene-S-C(S)-NR.sup.3 R.sup.4.
The use of dithiocarbamates as extreme pressure antiwear additives is also taught by U.S. Pat. No. 4,859,352 and U.S. Pat. No. 4,648,985 teaches that the combination of dithiocarbamates with zinc dithiophosphate and copper salts of carboxylic acid provide lubricants with extreme pressure properties.
The use of methylene bis(dibutyldithiocarbamate) as an oxidation inhibitor in lubricating oils, in combination with other ingredients, is also disclosed in U.S. Pat. Nos. 4,125,479 (1978) and 4,880,551 (1989).
U.S. Pat. No. 4,879,054 (1989) is directed to cold temperature greases and teaches using dithiocarbamates such as Vanlube 7723, i.e., 4,4'-methylene bis(dithiocarbamate), in such greases to provide extreme pressure antiwear properties (Col. 6, lines 18-28). Examples 13-18 (Col. 14, lines 26-32) describe using Vanlube 7723 and triarylphosphate as replacements for lead naphthenate and zinc dithiophosphate.
My prior U.S. Pat. Nos. 4,389,400; 4,427,667 and 4,447,450 disclose certain halogenated dithioethylene derivatives which are useful as agricultural fungicides.